The present invention relates to a vehicle seat.
Such vehicle seat includes a seat part as well as a backrest structure coupled with the seat part. The seat part usually comprises a seat base which carries a seat cushion. The backrest structure comprises a backrest frame on which a backrest cushion is arranged for supporting the back of a seat user.
The backrest structure regularly is pivotally mounted relative to the seat part, in order to permit an adjustment of the swivel position of the backrest corresponding to the needs of the seat user and/or to provide for folding of the backrest onto the seat part. In a proper position of use of the backrest structure, in which the backrest can serve the support of the back of a seat user, the backrest structure is arrested in its position relative to the seat part.
In particular in a rear-end impact it was found to be advantageous to permit a displacement of the backrest structure relative to the seat part under a permitted plastic deformation of components provided therefor. The objective here is to reduce the loads caused on the occupant due to the acceleration, which otherwise would result in a serious cervical spine trauma. The seat part and the backrest structure each are connected with a seat component, which seat components are coupled with each other via a deformation device, so that in a proper position of use of the backrest structure the two seat components are fixed to each other and only in the case of a crash—upon exceedance of a specified threshold value of a force acting on the backrest structure—a displacement of the seat component associated to the backrest structure relative to the seat component fixed at the seat part is permitted by selectively deforming a deformation element.
From DE 10 2008 019 917 B3, for example, it is known to provide a deformation device in the form of a device absorbing a rear-end crash active energy with a deformation element forming two oblong holes. Two screw bolts, which are provided at the seat component of the seat part, preferably each engage in one of the two oblong holes of the deformation element, which is rigidly and immovably fixed at the seat component associated to the backrest structure. The width of the oblong holes each is chosen smaller than the diameter of the respectively associated screw bolt, so that the two screw bolts are fixed in the oblong holes in an ordinary position of use of the vehicle seat. When during a rear-end impact an increased force exceeding a specified threshold value now acts on the backrest structure, the screw bolts can be shifted in the associated oblong holes by expanding the oblong holes. Due to this plastic deformation, crash energy is absorbed. Furthermore, the oblong holes specify a deformation path along which the seat component rigidly connected with the backrest structure (e.g. via a locked seat fitting) is shifted in the case of a crash.
The vehicle seat proposed in DE 10 2008 019 917 B3 however appears to be disadvantageous in so far as the permitted deformation path is defined via a component which also carries parts of a backrest adjusting means and hence also must be designed correspondingly for these requirements. Thus, the deformation element possibly cannot optimally be adapted to the deformation desired in the case of a crash via its material properties or its geometry.
In addition, it cannot easily be ensured that in normal operation there is no slight expansion of the two oblong holes. The screw bolts then possibly no longer are arrested in the oblong holes, so that the seat component of the backrest structure or the deformation element fixed thereto do not permanently remain in a specified position with respect to the seat component to be rigidly fixed at the seat part.